Magnetic measurement has conventionally been performed to know the orientation and the like. For example, electronic compasses and other similar devices measure a three-dimensional magnetic vector to know the accurate orientation. Measurement of the magnetic vector is performed by a magnetic sensor. Examples of such magnetic sensors include Hall elements and MR elements. In recent years, MI elements are focused on, which are entirely different in the structure and principle from such conventional elements and have incomparably high sensitivity.
MI elements utilize a magneto-impedance effect (referred to as an “MI effect”) that, when a high frequency pulse current or the like is caused to flow through a magneto-sensitive wire such as an amorphous wire, its impedance varies in accordance with a magnetic field due to a skin effect. Magnetic measurement of an external magnetic field and the like is possible by directly measuring the impedance variation and/or by indirectly measuring the variation of amount of magnetic flux generated in the magneto-sensitive wire, which causes the MI effect, via a detection coil (pickup coil) wound around the magneto-sensitive wire.
It should be noted, however, that MI elements can basically detect only a magnetic field component in the direction in which the magneto-sensitive wire extends. Therefore the conventional MI sensor, as in Patent Literature 1, has to be provided with an individual MI element for each of components of the magnetic vector to detect. For example, when measuring the three-dimensional components of an external magnetic field, it may be necessary to provide an MI element for X-axis and an MI element for Y-axis on the substrate plane (X-Y plane) and an MI element for Z-axis in the orthogonal direction to the substrate plane. This MI element for Z-axis has a certain length in the Z-axis direction like the other MI elements because of its structure. Accordingly, the conventional three-dimensional magnetic detection device is intrinsically difficult to be reduced in size and thickness in the Z-axis direction.
Nowadays, however, MI sensors incorporating MI elements have already been built in various handheld information terminals, etc. and are required to have high performance (high sensitivity and high accuracy) and to be further reduced in size. To this end, Patent Literature 2 proposes to omit the MI element for Z-axis and allow the MI element for X-axis and the MI element for Y-axis to measure the magnetic field component in the Z-axis direction.